A
disc of
unit radius on a
plane is called a
unit disc. Unless otherwise specified, the unit disc on a
Cartesian plane[?] is the unit disc about the origin. The unit disc may be either closed or open, that is to say, either be
- closed: the set of points with radius less than or equal to one from the centre
- open: the set of points with radius less than one from the centre
See also: open interval, closed interval, open set, closed set